1. Field of the Invention
The present invention relates to novel organopolysiloxane compositions that are stable in storage in the absence of moisture, but curable into elastomeric state in the presence of moisture, and which comprise, as the essential constituents thereof, an .alpha.,.omega.-dihydroxydiorganopolysiloxane polymer, a ketiminoxysilane crosslinking agent and an inorganic filler material; such novel compositions properly crosslink into elastomeric state in the absence of any organometallic curing catalyst.
2. Description of the Prior Art
Single-component organopolysiloxane compositions containing a ketiminoxysilane crosslinking agent, typically also comprising an inorganic filler and a curing catalyst, have long been known to this art. They are described, for example, in French Patents FR-A-1,314,649, FR-A-1,371,250, in U.S. Pat. Nos. 3,678,003 and 3,986,999, in British Patent GB-A-1,468,467, in Belgian Patent BE-A-901,479 and in European Patent EP-A-157,580.
These compositions are employed especially for coating and sealing applications, and in particular as sealants in the construction industry for producing glazed structures.
They can also be employed in the form of dispersions in organic diluents for producing various coatings.
It is also known, furthermore, from FR-A-2,074,144, to add an aminofunctional silane to such type of composition. In addition, the incorporation of hydroxylamine in silicone compositions containing an alkoxysilane crosslinking agent has been described, for example, in EP-A-70,786, and U.S. Pat. Nos. 3,770,847 and 3,847,848.
For certain special applications such as food-contact applications, medical applications and "antifouling" (antisoiling) coating applications, a need exists in this art for compositions of the above type which can crosslink without any organometallic catalyst, in particular in the absence of any organotin compound.
Another reason for avoiding such organotin compound is because compositions of the above type very often contain an organopolyalkoxysilane which bears a primary amine functional group; it is known to this art (see, for example, EP-A-184,966 and EP-A-267,126) that the silane/tin pair adversely affects the storage stability of such compositions.